There are a lot of negative stereotypes surrounding London real estate agents. Perhaps the most common one is of the eager/sleazy salesman trying to make a quick buck by selling anything he can, regardless of price or quality of the property.
Blake Stanley is not like that. Indeed, it is the exact opposite, but this doesn't mean it's a good agency. I found them inattentive, slow to get back to inquiries or e-mails and to book viewings. Also one of the agents was ambiguous at best, verbally agreeing to an offer made, but backtracking later once he got a higher offer.
My feeling in general was that if you're a young professional who is not on the top of the chain of renters or buyers (ie you don't have a wealthy parent who is financing your artistic pursuit/unrecognised musical talent by getting you a three-bed flat in bdway mkt) then you're not treated well there.
Their appeal is simply that they have some flats in what is considered a trendy area. But if you're willing to look in other areas aside from London Fields/bdway mkt, you're better off using another agency - contrary to overall public opinion, there are quite a few decent small real estate agencies out there.